Various kinds of organic and inorganic chleating agents have been used as detergent compositions, dispersing agents, coagulating agents, water treatment agents (anti-scale agents), chleating reagents, fiber treatment agents, bleaching assistants for wood pulp, pH adjusting agents, detergents, etc.
Of all the chleating agents, polymers based on carboxylic acid (organic chleating agent), produced by polymerizing a monomer of maleic acid or acrylic acid, are known to render excellent chleating and dispersing effects on inorganic particles, and therefore have been used in diversified fields. Organic chleating agents, such as ethylenediaminetetraacetate and nitrilotriacetate, are known to render relatively high ability in effectively capturing heavy metal ions.
However, in the polymers based on carboxylic acid produced by polymerizing a monomer of maleic acid or acrylic acid, a carboxyl group bonds directly to the main chain, and for this reason, the main chain inhibits free rotation of the carboxyl group. Thus, such polymers based on carboxylic acid renders unsatisfactory ability in capturing metal ions, especially, heavy metal ions.
The organic chleating agents, such as ethylenediaminetetraacetate and nitrilotriacetate, capture a relatively small amount of metal ions per unit weight, and the dispersing effect of the same on inorganic particles is insufficient to meet the demand from all the uses (fields).
Thus, there has been an increasing need for a chleating agent suitably used in diversified fields, that is, a compound which has an excellent dispersing effect on inorganic particles, high heavy metal ion capturing ability besides being capable of capturing a large amount of metal ions per unit weight. In addition, such a chleating agent is expected to render excellent biodegradability.